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Maize (Zea Mays L.) Kernel Development, Suitability For Dry-Grind Ethanol Production, And Susceptibility To Aflatoxin Accumulation In Relation To Late-Season Water Stress, Jason Wade Haegele Jan 2008

Maize (Zea Mays L.) Kernel Development, Suitability For Dry-Grind Ethanol Production, And Susceptibility To Aflatoxin Accumulation In Relation To Late-Season Water Stress, Jason Wade Haegele

Retrospective Theses and Dissertations

Worldwide, water stress during vegetative and reproductive development of cereal species is a primary constraint to crop yield. In maize ( Zea mays L.), environmental stresses such as high temperature and drought affect yield by reducing the number and mean dry weight of harvested seeds per unit area. Total grain yield is of great economic concern, and increasing yield under optimal and stress conditions has historically received the most attention by public and private breeding programs. But environmental effects on grain quality is of equal importance as maize production becomes more focused on end-user traits specifically for utilization in markets such ...


Molecular, Genetic, Physiological And Biochemical Studies Of 3-Methylcrotonyl-Coa Carboxylase And Biotin Carboxyl Carrier Protein-Like Proteins In Arabidopsis Thaliana, Geng Ding Jan 2008

Molecular, Genetic, Physiological And Biochemical Studies Of 3-Methylcrotonyl-Coa Carboxylase And Biotin Carboxyl Carrier Protein-Like Proteins In Arabidopsis Thaliana, Geng Ding

Retrospective Theses and Dissertations

Biotin-containing enzymes are involved in metabolic reactions that are essential for normal cellular functions in all organisms. In plants, four biotin-containing enzymes have been identified to date: homomeric acetyl-CoA carboxylase, heteromeric acetyl-CoA carboxylase, 3-methylcrotonyl-CoA carboxylase (MCCase), and geranoyl-CoA carboxylase. This dissertation contains two studies that are both part of the biotin metabolic network. The first study is the functional reverse genetic analysis of MCCase in Arabidopsis. MCCase is a nuclear-encoded, mitochondrial-localized enzyme. The reaction catalyzed by this enzyme is required for leucine (Leu) catabolism in mitochondria, and it may also play a role in the catabolism of isoprenoids and in ...


Understanding The Biological Activity Of Hypericum Species Through Metabolomics Studies, Matthew Lee Hillwig Jan 2008

Understanding The Biological Activity Of Hypericum Species Through Metabolomics Studies, Matthew Lee Hillwig

Retrospective Theses and Dissertations

The Hypericum genus contains plants which biosynthesize various polyketides with various known and unknown biological and medicinal activities. However, many Hypericum species have not been chemically or biochemically characterized. These species represent an opportunity for understanding chemical ecology and for new drug discovery research. Acyl-phloroglucinols are of particular interest since they are the most diverse class of specialized metabolites in Hypericum. We used analytical methods such as HPLC, LC-MS and 2-D NMR to screen Hypericum species for metabolite diversity. One species, H. gentianoides, was investigated further based on its historical use by Native Americans and its unique metabolite fingerprint. This ...


Functional Characterization Of Arabidopsis Sorting Nexin Atsnx2b, Nguyen Phan Jan 2008

Functional Characterization Of Arabidopsis Sorting Nexin Atsnx2b, Nguyen Phan

Retrospective Theses and Dissertations

Sorting nexins are conserved proteins that function in vesicular trafficking and are defined by the presence of a phox (PX) domain. Here we present the characterization of Arabidopsis thaliana sorting nexin AtSNX2b. The ubiquitously-expressed sorting nexin is a peripherally-associated membrane protein whose PX domain binds to phosphatidylinositol 3-phosphate in vitro. AtSNX2b localizes to the trans-Golgi network (TGN), prevacuolar compartment and endosomes. Overexpression of GFP-tagged AtSNX2b produces enlarged GFP-labeled compartments that can be also labeled by the endocytic tracer FM4-64, while untagged AtSNX2b overexpression generates compartments which are not as large. Endocytic trafficking of FM4-64 is arrested in cells overexpressing AtSNX2b ...


Laser Desorption/Ionization Mass Spectrometry For Direct Profiling And Imaging Of Small Molecules From Raw Biological Materials, Sangwon Cha Jan 2008

Laser Desorption/Ionization Mass Spectrometry For Direct Profiling And Imaging Of Small Molecules From Raw Biological Materials, Sangwon Cha

Retrospective Theses and Dissertations

Matrix-assisted laser desorption/ionization(MALDI) mass spectrometry(MS) has been widely used for analysis of biological molecules, especially macromolecules such as proteins. However, MALDI MS has a problem in small molecule (less than 1 kDa) analysis because of the signal saturation by organic matrixes in the low mass region. In imaging MS (IMS), inhomogeneous surface formation due to the co-crystallization process by organic MALDI matrixes limits the spatial resolution of the mass spectral image. Therefore, to make laser desorption/ionization (LDI) MS more suitable for mass spectral profiling and imaging of small molecules directly from raw biological tissues, LDI MS ...


Biochemical And Genetic Analyses Of Physical Associations Among Zea Mays Starch Biosynthetic Enzymes, Tracie Ann Hennen-Bierwagen Jan 2008

Biochemical And Genetic Analyses Of Physical Associations Among Zea Mays Starch Biosynthetic Enzymes, Tracie Ann Hennen-Bierwagen

Retrospective Theses and Dissertations

Mutations affecting specific starch biosynthetic enzymes commonly have pleiotropic effects on other enzymes in the same metabolic pathway. Such genetic evidence indicates functional relationships between components of the starch biosynthetic system including starch synthases (SS), starch branching enzymes (BE), and starch debranching enzymes (DBE), however, the molecular explanation for these functional interactions is not known. One possibility is that specific SSs, BEs, and/or DBEs associate physically with each other in multisubunit complexes. To test this hypothesis, this study sought to identify stable associations between SSI, SSIIa, SSIII, SBEI, SBEIIa, and SBEIIb from maize amyloplasts. Three separate detection methods, yeast ...


A Study Of The Impact Of Mazie Sbe I On The [Alpha]-Polyglucan Produced In Synechocystis Sp. Strain Pcc 6803, Shayani Deborah Nesaranjani Pieris Jan 2007

A Study Of The Impact Of Mazie Sbe I On The [Alpha]-Polyglucan Produced In Synechocystis Sp. Strain Pcc 6803, Shayani Deborah Nesaranjani Pieris

Retrospective Theses and Dissertations

Starch is a biopolymer synthesized primarily in plants and is made of alpha-1,4 linked glucose chains with alpha-1,6 glycosidic bonds at branch points. Amylose and amylopectin, the component molecules of starch are essentially linear and 4-5% branched respectively. Amylopectin, thought to be responsible for the semi-crystalline nature of starch, is chemically similar but physically distinct from water-soluble glycogen. Amylopectin is distinct from glycogen in having longer chains, fewer branch points and a clustered branching pattern. The hypothesis that the presence of a branching enzyme that can transfer long branches will facilitate the formation and perpetuation of a cluster ...


Phytoremediation Of Landfill Leachate Using Populus, Jill Annette Zalesny Jan 2007

Phytoremediation Of Landfill Leachate Using Populus, Jill Annette Zalesny

Retrospective Theses and Dissertations

Resource managers are challenged with waste disposal and leachate produced from its degradation. Poplar (Populus spp.) trees offer an opportunity for ecological leachate disposal as an irrigation source for managed tree systems. Information about sodium (Na+), chloride (Cl -), and nutrient uptake and distribution into tissues of Populus genotypes irrigated with landfill leachate helps to maximize biomass production and to understand impacts of leachate chemistry on tree health. However, such knowledge about the response of poplar genotypes to landfill leachate irrigation is limited, along with efficient methods for choosing genotypes based on leachate composition.;During initial greenhouse research, poplar clones were ...


Starch Function In Ornamental Tobacco Floral Nectary Development, Gang Ren Jan 2007

Starch Function In Ornamental Tobacco Floral Nectary Development, Gang Ren

Retrospective Theses and Dissertations

Morphological changes of floral nectary gland and subcellular transition of floral nectary cells of ornamental tobacco LxS8 were exclusively investigated in this study. Enlargement of the floral nectary gland of ornamental tobacco LxS8 that occurs during development is accompanied by a major accumulation of Periodic Acid-Schiff's staining (PAS-staining) starch grains in nectary amyloplasts. Quantification of starch purified from the nectary at various stages of development showed little starch at an early developmental stage, soon thereafter the amount of starch increased dramatically, reaching a peak approximately 24 hours prior to anthesis. After this time, the amount of starch declined dramatically ...


Signaling Dynamics In Rice Expressing Constitutively Active Nicotiana Protein Kinase 1 (Npk1), Andréa Lu Scarpa Jan 2007

Signaling Dynamics In Rice Expressing Constitutively Active Nicotiana Protein Kinase 1 (Npk1), Andréa Lu Scarpa

Retrospective Theses and Dissertations

Signaling components such as mitogen-activated protein kinases (MAPKs) regulate stress-induced pathways and are potentially a powerful means of genetically engineering plant tolerance to abiotic stress. The kinase domain of tobacco mitogen-activated protein kinase Nicotiana protein kinase 1 (NPK1) into rice cultivar Nipponbare. Four-week old transgenic and wild type plants treated with moderate (150mM) or severe (300mM) salt stress did not differ in visible signs of leaf damage, electrolyte leakage, malondialdehyde content or ion content within leaves. Expression of caNPK1 alters gene transcript abundance in the absence of stress as assessed by microarray analysis. Genes potentially related to flowering and development ...


Function Of Autophagy In Development And Abiotic Stress Tolerance In Arabidopsis Thaliana , Yan Xiong Jan 2006

Function Of Autophagy In Development And Abiotic Stress Tolerance In Arabidopsis Thaliana , Yan Xiong

Retrospective Theses and Dissertations

Autophagy is a process in which cytoplasmic components are degraded in the vacuole. It occurs when organisms are subjected to environmental stress conditions or during certain stages of development. Upon induction of autophagy, a portion of cytoplasm is surrounded by a double membrane structure to form an autophagosome. The outer membrane of the autophagosome then fuses with the vacuole and the inner membrane and its contents are degraded by vacuolar hydrolases. The morphological characteristics of autophagy have been observed in plants for decades and several autophagy defective mutants have been isolated recently; however, little is known about the molecular mechanism ...


Relationship Between Concentration Of Isoflavones In Soybean Grain And Potassium Fertilization , Mario Valadez Ramirez Jan 2006

Relationship Between Concentration Of Isoflavones In Soybean Grain And Potassium Fertilization , Mario Valadez Ramirez

Retrospective Theses and Dissertations

Soybean grain contains isoflavones that may prevent various human diseases. Previous studies in Canada found that K fertilization and high grain K concentration can result in increased isoflavones concentration in grain, but effects were inconsistent across sites and soil-test K (STK) levels. The objective of this study was to assess (1) effects of K fertilization on the concentration of isoflavones and K in soybean grain and (2) relationships between soybean grains K concentration, isoflavone concentration, and yield. The study was based on analyses of grain collected from selected treatments and years of six Iowa long-term experiments that investigated effects of ...


The Roles Of Aldehyde Dehydrogenases (Aldhs) In Acetyl-Coa Biosynthesis And Root Elongation In Arabidopsis , Yanling Wei Jan 2006

The Roles Of Aldehyde Dehydrogenases (Aldhs) In Acetyl-Coa Biosynthesis And Root Elongation In Arabidopsis , Yanling Wei

Retrospective Theses and Dissertations

Aldehyde dehydrogenases (ALDHs, EC 1.2.1) oxidize aldehydes into carboxylic acids, and thus are important in regulating the level of toxic aldehydes. ALDHs from eukaryotes were classified into more than 20 families. In mammals Family 2 ALDHs detoxify acetaldehyde and a similar function has been suggested in plants. Specifically, it has been hypothesized that plant Family 2 ALDHs oxidize acetaldehyde generated via ethanolic fermentation and produce acetate for acetyl-CoA biosynthesis through acetyl-CoA synthetase (ACS) in plastids, similar to the yeast pathway termed the "pyruvate dehydrogenase (PDH) bypass". Arabidopsis. thaliana contains three Family 2 ALDHs, two of which are mitochondrial ...


Functional And Expression Analysis Of Heteromeric Acetyl-Coa Carboxylase Subunit Genes Of Arabidopsis , Xu Li Jan 2005

Functional And Expression Analysis Of Heteromeric Acetyl-Coa Carboxylase Subunit Genes Of Arabidopsis , Xu Li

Retrospective Theses and Dissertations

Plant heteromeric acetyl-CoA carboxylase (htACCase) catalyzes the first and committed reaction of de novo fatty acid biosynthesis in plastids. Arabidopsis htACCase consists of five subunits: BCCP-1, BCCP-2, BC, alpha-CT, and beta-CT. They were encoded by CAC1-A, CAC1-B, CAC2, CAC3, and accD genes, respectively. The expression of these five genes was studies by real-time RT-PCR and quantitative western analysis. At the mRNA level, CAC1-A, CAC2, CAC3, and accD genes are expressed at a constant molar ratio of 0.5:1.0:0.2:2.0 across all the organs examined, but the expression pattern of CAC1-B is different. At the protein ...


Carbohydrate Partitioning And Photosynthesis In Arabidopsis Thaliana , Dan Joseph Stessman Jan 2004

Carbohydrate Partitioning And Photosynthesis In Arabidopsis Thaliana , Dan Joseph Stessman

Retrospective Theses and Dissertations

To characterize carbohydrate partitioning and photosynthesis in Arabidopsis thaliana we examined three different lines: wild type Columbia ecotype, immutans, and T-DNA knockouts of vacuolar acid invertase. Wild type plants displayed decreasing photosynthesis from the beginning of leaf expansion through senescence. Chlorophyll, total soluble protein, and expression of LhcB also declined in a similar fashion. Pulse-label feeding of 14C showed a peak flux into glucose and fructose coincident with full leaf expansion a large decrease in LhcB expression. However, flux of 14C into the different carbohydrate fractions did not reflect carbohydrate pool sizes. The conclusion was that flux into the different ...


Investigating The Influence Of Cadmium Stress On Glutathione Metabolism Utilizing Mutant And Transgenic Arabidopsis Plants , Annita Gatherum Peterson Jan 2004

Investigating The Influence Of Cadmium Stress On Glutathione Metabolism Utilizing Mutant And Transgenic Arabidopsis Plants , Annita Gatherum Peterson

Retrospective Theses and Dissertations

Glutathione (GSH) has long been known to be an essential molecule in a number of important basic cellular functions including detoxification of reactive oxygen species, transport and storage of organic sulfur, and regulation of the cell cycle. Furthermore, GSH is essential in the detoxification of some heavy metals including cadmium through the production of phytochelatins. Because the accounts of heavy metal pollution are increasing due to human activities, heavy metal toxicity in plants is an important topic of study. To investigate the role of GSH-related functions in response to cadmium exposure I examined three distinct levels of GSH involvement in ...


Three Amino Acid Loop Extension (Tale) Transcription Factors That Regulate Potato (Solanum Tuberosum L) Tuberization , Hao Chen Jan 2003

Three Amino Acid Loop Extension (Tale) Transcription Factors That Regulate Potato (Solanum Tuberosum L) Tuberization , Hao Chen

Retrospective Theses and Dissertations

Homeodomain (HD) proteins play an important role in cell fate determination and body plan definition by binding to regulatory regions of key target genes. Using the yeast two-hybrid system and a potato KNOX HD protein, POTH1, as bait, seven distinct interacting proteins have been identified from a potato (Solanum tuberosum L.) stolon library. All seven cDNAs belong to the BEL1-like family of transcription factors. Through deletion mutation analysis, we identified a protein-binding domain present in the carboxy-end of the KNOX domain of POTH1. The protein-binding domain in the BEL protein is located in the amino-terminal half of the 120-residue conserved ...


Identification And Characterization Of Proteins Expressed In The Nectar Of Ornamental Tobacco , Clay Jeremy Carter Jan 2002

Identification And Characterization Of Proteins Expressed In The Nectar Of Ornamental Tobacco , Clay Jeremy Carter

Retrospective Theses and Dissertations

A small set of proteins, termed Nectarins, are secreted into the nectar of ornamental tobacco (Nicotiana langsdorffii x Nicotiana sanderae). The most highly expressed protein, Nectarin I (29 kD monomer), was originally identified as a germin-like protein (GLP) of unknown function. This remarkably stable protein was later shown to possess manganese dependent superoxide dismutase activity. Hydrogen peroxide, the product of SOD activity, was found to accumulate in nectar at levels up to 4 mM. The promoter (1.2 kb) of the Nectarin I gene was fused to the reporter gene chloramphenicol acetyl transferase (CAT) and shown to be expressed in ...


The Structure-Function Relationships Of Maize Starch Synthase, Zhong Gao Jan 2001

The Structure-Function Relationships Of Maize Starch Synthase, Zhong Gao

Retrospective Theses and Dissertations

This research was to study the structure-function relationships and catalytic mechanisms of maize starch synthase IIa (SSIIa). Chemical modification of maize SSIIa showed that pyridoxal-5-phosphate, which specifically modifies lysine residues, inactivated maize SSIIa activity in a time and concentration dependent manner. Substrate ADP-glucose completely protected SSIIa from inactivation by pyridoxal-5-phosphate, indicating that lysine residue(s) is important for ADP-glucose binding of maize SSIIa. To identify lysine residues possibly involved in substrate ADP-glucose binding, site-directed mutagenesis was used to generate mutants at conserved lysine sites. Lysine-193 located at the conserved KTGGL domain has been widely suggested as a putative ADP-glucose binding ...


Insertional Mutagenesis Of The Signal Transduction Pathway For Low Co2 Acclimation In Chlamydomonas Reinhardtii , Kyujung Van Jan 2001

Insertional Mutagenesis Of The Signal Transduction Pathway For Low Co2 Acclimation In Chlamydomonas Reinhardtii , Kyujung Van

Retrospective Theses and Dissertations

Chlamydomonas reinhardtii shows adaptive changes in order to survive in limiting CO2 conditions because they live in quite variable conditions of CO2 availability. We are trying to identify mutants defective in the acclimation response to limiting CO 2. Nuclear transformation to complement an Arg- phenotype was used to generate insertional mutants, and Cah1 expression and having high CO2-requiring (HCR) phenotype were used as reporters for induction of genes involved in acclimation to limiting CO 2.;Among a collection of insertionally generated mutants, a mutant has been isolated that showed no pCA1 protein and no Cah1 mRNA. This mutant strain, designated ...


Growth And Water Relations Of Bt And Non-Bt Corn Plants Subjected To Soil Moisture Stress , Seydou Brehima Traore Jan 1999

Growth And Water Relations Of Bt And Non-Bt Corn Plants Subjected To Soil Moisture Stress , Seydou Brehima Traore

Retrospective Theses and Dissertations

A study was conducted at the Iowa State University Hinds Irrigation Farm, Ames, IA during the summers of 1997 and 1998 to compare the Bt and non-Bt versions of two maize (Zea mays, L.) hybrids. The plants were grown in buried, one meter deep, containers filled with a Nicollet loam (Aquic Hapludoll) soil. A rainout shelter protected the plots from the interruption of water deficit by rainfall. Irrigation was scheduled so that the plants experienced water deficit during the peak egg hatch of the first and second European corn borer, Ostrinia nubilalis (Hubner) generations. Water deficit during the vegetative period ...


Effects Of Stress Temperatures Of Germination On Polyamine Titers Of Soybean Seeds , Renan Pineda Mejia Jan 1999

Effects Of Stress Temperatures Of Germination On Polyamine Titers Of Soybean Seeds , Renan Pineda Mejia

Retrospective Theses and Dissertations

High and low stress temperatures during seed germination and seedling development limit total germination and the rate of germination and growth. Changes in polyamine (PA) concentrations in seeds of different species have been associated with germination, growth and environmental stresses such as temperature, drought, oxygen, chilling injury and osmotic conditions. Two studies were conducted to determine the effect of stress temperatures during germination and seedling development on polyamine titers in soybean seeds. Three germination temperatures, 25, 30, and 36 0C were used in the first study to evaluate their influence on changes in polyamine concentrations in soybean seeds germinated at ...


Physicochemical Properties Of Selected Root And Tuber Starches And Characterization Of Extruded, Chemically Modified Corn Starches , Andrew Edward Mcpherson Jan 1999

Physicochemical Properties Of Selected Root And Tuber Starches And Characterization Of Extruded, Chemically Modified Corn Starches , Andrew Edward Mcpherson

Retrospective Theses and Dissertations

The physicochemical properties of normal potato, waxy potato, yam and sweet potato starches were examined and compared. Normal potato and waxy potato starches displayed the B-type x-ray diffraction pattern, whereas yam and sweet potato displayed the CA- and C-type, respectively. X-ray diffraction patterns of Naegeli dextrins of normal potato and waxy potato remained the B-type, but those of yam and sweet potato changed to the A-type. 31P-NMR showed the phosphorus contents of the starches to be primarily phosphate monoesters with no detectable phospholipid in any of the four starches. Normal potato and waxy potato starches displayed lower proportions (13 and ...


Variation In Alfalfa (Medicago Sativa L.) For Germination And Seedling Vigor At Suboptimal Temperatures: And Laboratory And Field Response To Selection Within Six Alfalfa Populations , Kathy Lynn Esvelt Klos Jan 1999

Variation In Alfalfa (Medicago Sativa L.) For Germination And Seedling Vigor At Suboptimal Temperatures: And Laboratory And Field Response To Selection Within Six Alfalfa Populations , Kathy Lynn Esvelt Klos

Retrospective Theses and Dissertations

Establishment of alfalfa stands planted in the early spring requires rapid germination and vigorous seedling growth at cool temperatures. The extent of variation among ten alfalfa cultivars, 'Marathon' red clover, and 'Norcen' birdsfoot trefoil for germination time and radicle growth rate at 5, 10, and 15 C was evaluated, variation for germination time at 5 and 10 C among seven alfalfa cultivars was compared with variation among seed lots within these cultivars, and same of these cultivars were evaluated for field emergence. The initial radicle growth rate of cultivars increased with temperature, and the germination time of cultivars and of ...


Changes In Physiology, Molecular Biology, And Biochemistry Associated With Maize Seedlings Germinated From Freeze-Damaged Seed , Jack Alan Hartwigsen Jan 1999

Changes In Physiology, Molecular Biology, And Biochemistry Associated With Maize Seedlings Germinated From Freeze-Damaged Seed , Jack Alan Hartwigsen

Retrospective Theses and Dissertations

Injury to immature maize seed caused by early season frost is of great economic concern to seed producers. Surprisingly, there has been very little research investigating the adverse effects of freezing on immature seed and the resulting biochemical changes in seedlings germinated from freeze damaged seed. In this three part study, we investigated the effects of freezing injury, first as they pertained to the overall viability of the seed, then to how exposure of immature seed to freezing induces biochemical changes in seedlings germinated from these seed. We found that the extent of freezing injury as determined by reduced viability ...


Dynamics Of Maize Endosperm Development , Anthony Onwuli Iheanyi Anaele Jan 1998

Dynamics Of Maize Endosperm Development , Anthony Onwuli Iheanyi Anaele

Retrospective Theses and Dissertations

An understanding of cellular events contributing to normal endosperm formation in the maize kernel may provide better models of the construction of grain yield. A commercial hybrid maize, Dekalb 580, was grown in a controlled environment to study dynamics of cellular events in three regions during endosperm development, and to ascertain if this genotype has an indeterminate pattern of endosperm cell division. Longitudinal sections in two planes of endosperm show uniform sizes for both nuclei and cells during the early stages of endosperm development. As endosperm develops, nuclei and cells become increasingly variable in size. In addition, cells acquire irregular ...


Sink-Pulled Simulation Of The Maize Crop , Samiha Abou El-Fetouh Hamed Ouda Jan 1998

Sink-Pulled Simulation Of The Maize Crop , Samiha Abou El-Fetouh Hamed Ouda

Retrospective Theses and Dissertations

Current maize simulation models (CORNF and CERES-Maize) are "source-oriented", in which kernel weight is predicted without simulating sink demand of the kernels. The major goal of this research is to develop a physiologically sound model to simulate vegetative and reproductive growth of maize;The objectives of this study are: (1) to develop a subroutine to predict maize vegetative development; (2) to develop mechanisms to calculate silk growth, fertilization of the silk, and kernel set; (3) to address some of the problems that CENTLI has and use it to simulate grain filling period; (4) to develop a mechanism to predict the ...


Seed Development Of Shrunken-2 Sweet Corn (Zea Mays L.) And The Use Of Film Coating And Field Chemical Applications To Improve Seed Quality , Xianming Duan Jan 1997

Seed Development Of Shrunken-2 Sweet Corn (Zea Mays L.) And The Use Of Film Coating And Field Chemical Applications To Improve Seed Quality , Xianming Duan

Retrospective Theses and Dissertations

This study investigated the impacts of shrunken-2 (sh2) endosperm mutation on sweet corn embryogenesis and germination acquisition during seed development and maturation. Comparison between three pairs of sh2 and sugary (su) isogenic inbred lines and two dent corn inbreds showed that sh2 not only reduced the endosperm reserve accumulation, but also significantly retarded embryo development, especially during early seed development, resulting in a smaller embryo after maturation. Developing seed of sh2 lines acquired the same germinability at least 10 days later than su and dent corn seeds. During the late maturation stage, the germinability of sh2 seeds tended to decline ...


Production, Evaluation, And Utilization Of Hybrid Soybean [Glycine Max (L.) Merr.] , Kimberly Suzanne Lewers Jan 1996

Production, Evaluation, And Utilization Of Hybrid Soybean [Glycine Max (L.) Merr.] , Kimberly Suzanne Lewers

Retrospective Theses and Dissertations

Soybean is an autogamous crop species, and the production of large numbers of hybrid seeds has been tedious. Nevertheless, hybrid seed is important to certain types of research. Insect pollination of male-sterile plants facilitates the production of hybrid soybean seed. A new method of hybrid soybean seed production, the Cosegregation Method, which was developed in this dissertation research, utilizes close genetic linkage between a male-sterility locus, Ms6, and a seedling marker locus, W1. This closely-linked marker system allows identification of male-sterile plants at the seedling stage and improves hybrid seed production through greater efficiency and higher yield of hybrid seed ...


Induction Of Tuber Gene Expression In Solanaceous Species By Methyl Jasmonate And Wounding , Tsu-Hwie Annie Liu Jan 1995

Induction Of Tuber Gene Expression In Solanaceous Species By Methyl Jasmonate And Wounding , Tsu-Hwie Annie Liu

Retrospective Theses and Dissertations

Two major research approaches have been used to study the tuber-related gene expressions in different Solanaceous species. The first part of the research is using Agrobacterium-mediated gene transformation to study potato proteinase inhibitor II (pinII) gene which highly expressed in developing tuber in a wild nontuberizing specie Solanum brevidens. To establish the transformation system, leaf pieces of in-vitro cultured S. brevidens were cocultivated with Agrobacterium tumefaciens that contained nptII and GUS genes on the disarmed plasmid pBI121. Independent transgenic shoots were regenerated from both solidified and liquid medium with kanamycin. Agrobacterium strains GV2260 resulted in a higher transformation frequency than ...